This invention relates to unsymmetrical azo compounds, unsymmetrical hydrazo compounds, processes for preparing these compounds and processes utilizing these compounds, which azo and hydrazo compounds are characterized by having a tertiary carbon atom joined to one of the azo or hydrazo nitrogens.
Symmetrical azo compounds having a tert-carbon atom joined to each azo nitrogen are known:
T. E. Stevens, J. Org. Chem. 26, 2531 (1961). PA0 E. Farenhorst and E. C. Kooyman, Rec. Trav. Chim. 72, 993 (1953). PA0 S. F. Nelson and P. D. Bartlett, J. Am. Chem. Soc. 88, 137, 143 (1966). PA0 M. C. Chaco and N. Rabjohn, J. Org. Chem. 27, 2765 (1962). PA0 D. C. Iffland, L. Salisbury, and W. R. Schafer, J. Am. Chem. Soc. 83, 747 (1961). PA0 D. Y. Curtin and J. A. Ursprung, J. Org. Chem. 21, 1221 (1956). PA0 C. G. Overberger and A. V. Di Giulio, J. Am. Chem. Soc. 80, 6562 (1958); ibid 81, 2154 (1959). PA0 H. Wieland, et al, Ann. 514, 145 (1934). PA0 Thiele, B. 28, 2600. PA0 Angeli, Rome Atti Accad Tincei 26 I, 95 (1917). PA0 Thiele and Strange, Ann 283, 33 (1894) PA0 D. Neighbors et al., J. Am. Chem. Soc. 44, 1557 (1922). PA0 A. General Procedure for All Ketones PA0 B. General Procedure for water soluble and partially soluble ketones. PA0 Canadian Patent No. 655,296 issued Jan. 1, 1963. PA0 J. C. Bevington and A. Wahid, Polymer 3, 585 (1962); ibid 4, 129 (1963). PA0 D. Neighbors, et al, J. Am. Chem. Soc. 44, 1561 (1922). PA0 H. Zollinger, "Azo and Diazo Chemistry, Aliphatic and Aromatic Compounds", Interscience, New York, N.Y., 1961, p. 327. PA0 Goldschmidt and Acksteiner, Ann. 618, 173 (1958) PA0 British Patent No. 988,253 issued Apr. 7, 1961 to Monsanto Co. PA0 Canadian Patent No. 750,380 issued Jan. 10, 1967 to Monsanto Co. PA0 H. Bock and J. Kroner, Chem. Ber. 99, 2039 (1966). PA0 K. E. Cooper and E. H. Ingold, J. Chem. Soc. 1926, 1894. ##STR48## It was unknown, prior to the present work, that a mono azo ester, such as [E], would react with primary and secondary amines (including ammonia) to form the corresponding azoformamide. PA0 J. Lakritz, "The Synthesis and Reactions of Sterically Hindered Hydrazines; And the Acid Catalyzed Rearrangement of Tertiary Cyclic Azides", University of Michigan, Ph.D. thesis, 1960, University Microfilms, Inc., Mio 60-6898. ##STR51## The [J] compounds cannot be oxidized to azo compounds. The formation of [G] rather than [J] when R is a tertiary alkyl group is due to the bulky nature of the tertiary group. This has been previously reported and [G] compounds are known but have never been oxidized to the azo compounds. The azo compounds [H] are very unstable and therefore difficult to isolate. PA0 A. Andraca, Anales quim farm 1941, p. 15. PA0 Pellizzari, Gazz. chim. ital. 16, 302 (1888) PA0 Pinner, Ber., 20, 2359 PA0 Beilstein, 15, 287 PA0 C. Vogelsang, Rec. trav. chim. 62, 5 (1943) PA0 K. A. Taipale and P. V. Usachev, J. Russ. Chem. Soc. 62, 1241-58 (1930)
Unsymmetrical azo compounds where a tert-carbon atom is joined to one azo nitrogen are known. Illustrative compounds of this type, none coming within the scope of the invention are given in:
The above compounds are in general difficult to prepare, or are so stable that they are not useful as free radical generators or as blowing agents for plastic foams.
2,2'-azobisisobutyronitrile is commercially available. This compound has the structure ##STR2## It has many shortcomings. It is a toxic solid. Moreover, the decomposition residue is a highly toxic solid. Thus, it presents a toxic dusting problem when used in commercial operations and extreme precautions are required in its handling. It is not used in many applications for which it is suited because other areas at the manufacturing site cannot tolerate even the remote chance of exposure to such toxic dust. This is especially true when manufacturing goods for the food and drug packaging industries and many other goods for the household consumer. It cannot be used as a blowing agent for the great majority of the plastic foam market due to the high levels of the toxic residue left in the foamed product. It is insoluble in petroleum hydrocarbon solvents and possesses very low or limited solubility in most of the organic common solvents such as aromatic hydrocarbons, dioxane, alcohol, ether and carbon tetrachloride. This insoluble nature eliminates its use for many applications for which it would otherwise be suitable. It presents problems of metering, incorporation, mixing, dispersing, etc. and necessitates the use of a solvent that in many cases is not ideally suited for the particular application.
The new compositions of the present invention eliminate these problems. Most of the new compositions are liquids and are soluble in petroleum hydrocarbon and most of the other common organic solvents. Thus, no dusting, metering, incorporating, mixing, and dispersing problems are encountered in using these new compositions. Also the new compositions and their decomposition residues have chemical structures that suggest that they are, for the most part, significantly less toxic. Preliminary toxicological studies on the new compositions made in Examples I and II, set out later, and the decomposition residue of the Example I product indicate that they are significantly less toxic than IXA and its decomposition residue. The less toxic nature of the new compositions coupled with their liquid and high solubility properties allows them to be used in many applications where IXA cannot be used.
Unsymmetrical tert-carbon containing hydrazo compounds are known. Illustrative literature showing the prior art types of these compounds is presented: